A common form of diarrhea, in which soft fecal matter and non digested food (most often lettuce or vegetables) covers much of the toilet's surface water, giving the appearance of a miniaturized marsh, swamp or bog within the bowl. It must then be allowed to linger; no flushing, until potency has been acquired and a second party has declared it to be such.

Also sometimes but rarely known as Bowel Bog

Alex is being a dick, I'm gonna go Shit Swamp his toilet. Wait 15 minutes and then go declare it.
or
If I find out which of you assholes just laid a Shit Swamp in my bathroom, I'll beat your nads in!